Effects of dust on the formation of lines in an expanding spherical medium

Abstract

A series of line profiles formed in a spherically symmetric and radially expanding atmosphere in which dust is present are computed, assuming that the dust scatters radiation isotropically. Two cases of dust distribution are employed: (1) uniform distribution of dust throughout the medium and (2) density increasing with radius. The density and the velocity of expansion of the gaseous component are assumed to satisfy the equation of continuity for a model of a two-level atom in a non-LTE approximation with complete redistribution. The calculations are done in the comoving frame of the fluid and later transformed to a point at infinity.